Availability of components: Easy to get, uses only very common basic components

Design testing: Based on datasheet example circuit, I have used this circuit succesfully as part of many electronics projects

Applications: Part of electronics devices, small laboratory power supply

Power supply voltage: Unreglated DC 8-18V power supply

Power supply current: Needed output current + 5 mA

Component costs: Few dollars for the electronics components + the input transformer cost

Circuit description

This circuit is a small +5V power supply, which is useful when
experimenting with digital electronics. Small inexpensive wall
tranformers with variable output voltage are available from any
electronics shop and supermarket. Those transformers are easily
available, but usually their voltage regulation is very poor,
which makes then not very usable for digital circuit experimenter
unless a better regulation can be achieved in some way. The
following circuit is the answer to the problem.

This circuit can give +5V output at about 150 mA current, but it can
be increased to 1 A when good
cooling is added to 7805 regulator chip. The circuit has over
overload and therminal protection.

Circuit diagram of the power supply.

The capacitors must have enough high voltage rating to safely handle
the input voltage feed to circuit. The circuit is very easy to build for
example into a piece of veroboard.

Modification ideas

More output current

If you need more than 150 mA of output current, you can update the
output current up to 1A doing the following modifications:

Change the transformer from where you take the power to the circuit to a model which can give as much current as you need from output

Put a heatsink to the 7805 regulator (so big that it does not overheat because of the extra losses in the regulator)

Other output voltages

If you need other voltages than +5V, you can modify the circuit by replacing
the 7805 chips with another regulator with different output voltage from
regulator 78xx chip family. The last numbers in the the chip code tells
the output voltage. Remember that the input voltage muts be at least 3V
greater than regulator output voltage ot otherwise the regulator does not
work well.